133321561 has 2 divisors, whose sum is σ = 133321562. Its totient is φ = 133321560.

The previous prime is 133321519. The next prime is 133321571. The reversal of 133321561 is 165123331.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 89019225 + 44302336 = 9435^2 + 6656^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-133321561 is a prime.

It is not a weakly prime, because it can be changed into another prime (133321571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 66660780 + 66660781.

It is an arithmetic number, because the mean of its divisors is an integer number (66660781).

Almost surely, 2^133321561 is an apocalyptic number.

It is an amenable number.

133321561 is a deficient number, since it is larger than the sum of its proper divisors (1).

133321561 is an equidigital number, since it uses as much as digits as its factorization.

133321561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1620, while the sum is 25.

The square root of 133321561 is about 11546.4956155537. The cubic root of 133321561 is about 510.8579190697.

Adding to 133321561 its reverse (165123331), we get a palindrome (298444892).

The spelling of 133321561 in words is "one hundred thirty-three million, three hundred twenty-one thousand, five hundred sixty-one".